Mechanical electrics, like relays, swithes, motors, etc, as voltage drops they just slow down or get weaker with the voltage.
Semi-Conductor, solid-state, electronic, transistors, computers, integrated circuit chips, etc, the semi-conductors in the circuits often a require a certain "gate" voltage for them to operate. Voltage drops below that "gate", the current won't flow through the particular semi-conductor component in the circuit and the circuit won't react like it should.
That is why, newer vehicles with more computers controlling everything, if voltage drops on the system, you get all sorts of random and weird reactions from the vehicle.
Cold increases the current draw of most electric items, Cold causes most owners to turn on more electrical equipment, like blower motor, defrost, AC for defrost, heated seats, etc, drawing even more current.
Draw more current than the alternator can supply, then the voltage will drop. It drops below the battery voltage, then the battery will start supplying current, and help the system out, but as the battery drains its voltage will drop and let the voltage of the whole system drop.
The motor at idle, like sitting at a light or in a traffic jam, also runs the alternator slower and it produces less current and makes it even more likely for voltage to drop with all the electric items on.
I'm really disappointed that Chrysler, and most of the Manufacturers, they no longer include electrical or oil gauges in their vehicles. I guess they figured the owner just didn't understood what they meant, therefore were a waste of time. BUT, if you had an electrical gauge, you could have been able to tell what was happening with the electrical system and could tell if your problem was merely supply vs demand problem.
That is the likely cause of the randomness, if you could tell your electrical system was drooping under the load, that would confirm.
Did the "Battery Light" come on at all? That is suppose to come on when the electric system voltage drops below 9 Volts, as well as other things.
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